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502 block
8.3K views 13 replies 8 participants last post by  matt wheeler  
#1 ·
Hey guys i just got a short block from a guy in houston its a bored 502 it is now 4.530 with a 4 inch stroke crank and 6.135 rods i was wondering if this was a good combo do to the fact that it needs new rods and pistons now would be the time to change it up. Im not real sure how much more i can have this block bored
 
#2 ·
If you are having to change the rods and pistons I would just go to a stroke kit, crank and all! With that bore I think with a 4.25 stroke crank you would be around a 547 or so! You probley have two more bores you can go safely!
 
#6 ·
Unless that is a bowtie or aftermarket block I thought the max bore on a factory 502 was 4.5"? Anybody know for sure, cause I have a HP500EFI 502 that I would like to open up more than 4.5" when necessary.
 
#9 ·
Mine is a bowtie
Then let the boring begin. You'll gain more from unshrouding the valves, by moving the cylinder walls away from the valves, than you will from the extra few inches, but it's a win win. No replacement for displacement.
 
#10 ·
I would need to double check, but I think GM was recommending .060" maximum over bore on the Gen 6 blocks. I know that's what they say on the Gen 6 454 blocks,, but one I looked at pretty carefully with the machinist at the shop seemed to have very thick walls.

I did a 4.530" bore on a Gen 6 502 block with a Whipplecharger on it a couple of years ago, it's been an impressive engine, honest 120+ mph on gps in a Stoker. I have done a couple of others to 4.530" and 4.250" stroke(548 cubic inch), but neither has any time on them yet except on the dyno.
 
#12 ·
mine is 4.500 with a 4.25 stroke, and i was told it had very thick cylinders, that could have gone as far as 4.530 with no issues. just no need to go that far. 4.25 cleared no problem without any work, or pan mods.
I fully agree that it's a good idea to only bore the minimum to clean up a block, so that you have a chance to bore the block in the future if necessary, not to mention maintaining adequate cylinder wall thickness.
 
#14 ·
502 bowtie

I have been told by many that the bowtie is good for 4.600 but like you guys said its all about the wall thickness if you go much more i would think filling it to the bottom of the water ports with filler would help some but i think im just going to leave my bore alone and just stroke it just a little to get the ci out of it. Thanks guys